Northampton Saints forward Calum Clark looks set to miss the Six Nations after it was confirmed on Tuesday that he will undergo surgery on his right shoulder.

Clark was added to England's elite player squad when the revamped selection was unveiled in January. The flanker-come-lock had previously endured a torrid year having been hit with a 32-week ban after he broke a player's arm in last season's Anglo-Welsh Cup final. With his ban at an end and having turned in a number of performances for Northampton this season, England coach Stuart Lancaster, who named Clark in his first EPS, recalled the forward and included him in the squad as a second-row ahead of the Six Nations.

But Clark hurt his shoulder in Northampton's loss to Glasgow at the weekend raising fears that he would miss out on the chance to make his debut for England in the forthcoming Six Nations. And that now seems a very real prospect. Northampton and England are reluctant to put a time frame on Clark's recovery but he Tweeted earlier in the day: "My shoulder needs an operation so I will be out of action for the foreseeable future. That's the game."

Saracens lock Mouritz Botha was called up by England to cover Clark's injury when the team met earlier this week. With Tom Palmer also sidelined, it looks likely that England will turn to the likes of Joe Launchbury, Geoff Parling and Courtney Lawes in the second-row for the forthcoming tournament.

Lancaster said of Clark's injury: "It is a shame for Calum as he had worked hard to get back into the senior squad. But these things happen and our medics will work closely with Northampton on his rehab."

England are also sweating on the fitness of Exeter forward Tom Johnson after he was stretchered off against Leinster on Saturday but his Chiefs coach Rob Baxter is optimistic that the flanker will be back in action in weeks rather than months.

"We don't think we're talking about major reconstructive surgery," Baxter the told BBC. "So as long as the MRI scan shows that and backs that up then there is a possibility it could be weeks of recovery rather than months.

"We know it's a relatively severe injury, he's not had an MRI scan yet which will give us a bit more detail. I think our feeling is the injury could have been worse than it is, but I don't want to say too much until he's had the complete scan results."